SnapshotUnpremultiplySource.h File Reference

Authoritative WGSL for the snapshot readback unpremultiply pass. More...

#include "donner/gpu/shader/wgsl/Compiler.h"

Include dependency graph for SnapshotUnpremultiplySource.h:

Namespaces
namespace	donner
	Top-level Donner namespace, which is split into different sub-namespaces such as donner::svg and donner::css.

Variables
constexpr wgsl::SourceText	donner::gpu::shader::programs::kSnapshotUnpremultiplySource
	Authoritative WGSL for the snapshot readback unpremultiply pass.

Detailed Description

Authoritative WGSL for the snapshot readback unpremultiply pass.

Variable Documentation

kSnapshotUnpremultiplySource

wgsl::SourceText donner::gpu::shader::programs::kSnapshotUnpremultiplySource

inlineconstexpr

Initial value:

{
    R"wgsl(@group(0) @binding(0) var inputTexture: texture_2d<f32>;
@group(0) @binding(1) var outputTexture: texture_storage_2d<rgba8unorm, write>;
 
@compute @workgroup_size(8, 8, 1)
fn cs_main(@builtin(global_invocation_id) gid: vec3<u32>) {
  let extent = min(textureDimensions(inputTexture), textureDimensions(outputTexture));
  if (any((gid.xy >= extent))) {
    return;
  }
  let coords = vec2<i32>(gid.xy);
  let premul = textureLoad(inputTexture, coords, 0i);
  let r8 = u32(round((premul.x * 255f)));
  let g8 = u32(round((premul.y * 255f)));
  let b8 = u32(round((premul.z * 255f)));
  let a8 = u32(round((premul.w * 255f)));
  var sr: u32 = 0u;
  var sg: u32 = 0u;
  var sb: u32 = 0u;
  if ((a8 != 0u)) {
    let halfAlpha = (a8 >> 1u);
    sr = min(255u, (((r8 * 255u) + halfAlpha) / a8));
    sg = min(255u, (((g8 * 255u) + halfAlpha) / a8));
    sb = min(255u, (((b8 * 255u) + halfAlpha) / a8));
  }
  let straight = vec4<f32>((f32(sr) / 255f), (f32(sg) / 255f), (f32(sb) / 255f), (f32(a8) / 255f));
  textureStore(outputTexture, coords, straight);
}
)wgsl"}

Authoritative WGSL for the snapshot readback unpremultiply pass.